Trace radioisotope

Radioisotope that occurs naturally in trace amounts

A trace radioisotope is a radioisotope that occurs naturally in trace amounts (i.e. extremely small). Generally speaking, trace radioisotopes have half-lives that are short in comparison with the age of the Earth, since primordial nuclides tend to occur in larger than trace amounts. Trace radioisotopes are therefore present only because they are continually produced on Earth by natural processes. Natural processes which produce trace radioisotopes include cosmic ray bombardment of stable nuclides, ordinary alpha and beta decay of the long-lived heavy nuclides, thorium-232, uranium-238, and uranium-235, spontaneous fission of uranium-238, and nuclear transmutation reactions induced by natural radioactivity, such as the production of plutonium-239^[1] and uranium-236^[2] from neutron capture^[3] by natural uranium.

Elements

The elements that occur on Earth only in traces are listed below.

Element name	Chemical Symbol
Technetium	Tc
Promethium	Pm
Polonium	Po
Astatine	At
Radon	Rn
Francium	Fr
Radium	Ra
Actinium	Ac
Protactinium	Pa
Neptunium	Np
Plutonium	Pu

Isotopes of other elements (not exhaustive):

References

^ Curtis, David; Fabryka-Martin, June; Paul, Dixon; Cramer, Jan (1999). "Nature's uncommon elements: plutonium and technetium". Geochimica et Cosmochimica Acta. 63 (2): 275–285. Bibcode:1999GeCoA..63..275C. doi:10.1016/S0016-7037(98)00282-8.
^ "Technical sheet about (nuclear) mass spectrometry" (PDF). Archived from the original (PDF) on 22 July 2011. Retrieved 28 August 2009.
^ Wilcken, K.~M.; Barrows, T. T.; Fifield, L. K.; Tims, S. G.; Steier, P. (June 2007). "AMS of natural ²³⁶ U and ²³⁹Pu produced in uranium ores". Nuclear Instruments and Methods in Physics Research B. 259 (1): 727–732. Bibcode:2007NIMPB.259..727W. doi:10.1016/j.nimb.2007.01.210. hdl:1885/29151. S2CID 96531059.

Periodic table

Periodic table forms

Standard	18-column 32-column
Alternative	Alternatives Janet's left step table
Extended	Extension beyond the 7th period Aufbau Fricke Pyykkö

Sets of elements

By periodic table structure

Groups	1 (Hydrogen and alkali metals) 2 (Alkaline earth metals) f-block groups 3 4 5 6 7 8 9 10 11 12 13 (Triels) 14 (Tetrels) 15 (Pnictogens) 16 (Chalcogens) 17 (Halogens) 18 (Noble gases)
Periods	1 2 3 4 5 6 7 8+ Aufbau Fricke Pyykkö
Blocks	s-block p-block d-block f-block g-block Aufbau principle

By metallicity

Metals	Alkali metals Alkaline earth metals Lanthanides Actinides Transition metals Post-transition metals
Metalloids	Lists of metalloids by source Dividing line
Nonmetals	Reactive nonmetals Noble gases

Other sets

Elements

Lists	By: Abundance (in humans) Atomic properties Nuclear stability Symbol
Properties	Aqueous chemistry Crystal structure Electron configuration Electronegativity Goldschmidt classification Term symbol
Data pages	Abundance Atomic radius Boiling point Critical point Density Elasticity Electrical resistivity Electron affinity Electron configuration Electronegativity Hardness Heat capacity Heat of fusion Heat of vaporization Ionization energy Melting point Oxidation state Speed of sound Thermal conductivity Thermal expansion coefficient Vapor pressure